Replace mutation target text node with a span element

Question

I am using MutationObserver to track character changes in my rich text editor. Everytime a text is edited, the mutation callback method is called with the list of mutation records. The mutation target is the text node in which changes are made. I want to wrap this text node with a span so that I can use some css to highlight changed text. However, this is not working for me. Can you please guide what am I doing wrong here?

function callback(mutations) {
    mutations.forEach(function(mutation){
        if(mutation.type == 'characterData'){
           let parentNode = mutation.target.parentElement;

           // Create the new node to insert
           let newNode = document.createElement("span");
           newNode.classList.add('change-highlighter');

           // appending existing text node to new span element
           newNode.appendChild(mutation.target);

           // inserting newNode before text node
           parentNode.insertBefore(newNode, mutation.target);         
        }
    });
  }

Matt Ellen · Accepted Answer · 2022-06-07 12:23:57Z

0

I would insert the span, then append the target.

function callback(mutations) {
    mutations.forEach(function(mutation){
        if(mutation.type == 'characterData'){
           let parentNode = mutation.target.parentElement;

           // Create the new node to insert
           let newNode = document.createElement("span");

           newNode.classList.add('change-highlighter');

           // inserting newNode before text node
           parentNode.insertBefore(newNode, mutation.target);

           // appending existing text node to new span element
           newNode.appendChild(mutation.target);
        }
    });
  }

edited Jun 7, 2022 at 12:23

answered Jun 7, 2022 at 12:01

Matt Ellen

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5 Comments

Saurabh Kulkarni Over a year ago

Thanks Matt! In my case, the previousSibling is also null, so it goes to parentNode.appendChild(newNode); However, I see bunch of mutation records being printed after made a text change, which are in the following sequence - Text node removed, span node added, remove text node under span, span node added and span node removed. The text I typed is getting moved automatically to a wrong position

Matt Ellen Over a year ago

Perhaps it's a lot more simple than I thought. you can insert the span, before the target, then add the target to the span.

Saurabh Kulkarni Over a year ago

Unfortunately, that gives the same behaviour. Here's the complete code that I am trying to run on w3school github.com/saurabhkulkarni26/testcode/blob/main/…

Matt Ellen Over a year ago

The editor is automatically removing the span from the DOM, so I don't think this is possible with the editor you are using.

Saurabh Kulkarni Over a year ago

You were right. The editor was the problem. I used a different editor and now it does not remove those nodes automatically. Thanks a lot!

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